Re: should i double baffle?

How well braced is the enclosure? What type of hardware are you using to mount the sub? Is the motor of the sub supported? These are all issues that are just as important, if not more so, that just doubling the baffle, and yes I would double the baffle.

Re: should i double baffle?

If you can afford it, and don't mind spending the extra time/cash, it wouldn't hurt. If you have heavy subs, and a poorly braced box, I would most definitely double baffle. At the same time, if you are currently in the progress of building, and have heavy subs, make sure you brace it well. Double baffles can also allow you to flush mount, which is always a nice added touch, even if you don't NEED to double baffle.

Re: should i double baffle?

Ditch the plywood, if you can't find MDF then get birch.

As far as the baffle goes, it depends on the size/shape of the box. if you have a 15" sub mounted on a 16x16 baffle I would say don't bother, if it's mounted on a 20x30 ish baffle then yes double it up.

Also proper bracing is key and if done right won't make a big dif to the sound.